Attachment plug



Aug. 15, 1939. A. BROWNSTEIN ATTACHMENT PLUG Filed June 1 1937 In m IINVENTOR Art/zarfirorrnsfecn BY fi:

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Patented Aug. 15, 1939 UNITED STATES PATENT OFFICE ATTACHMENT PLUGApplication June 1, 1937, Serial No. 145,759

6 Claims.

This invention relates to an electrical contact plug and moreparticularly to a resilient contact plug having blades therein which areadapted to be readily attached to an electrical conductor to connect thesame to an electrical outlet.

Attachment plugs are sometimes made of rubber or similar material whichin addition to being a good electrical insulator is not subject tofracture as is the usual molded resins, hard rubm ber and the like. Therubber being pliable and resilient, the blades can have a slight play toaccommodate outlets having slight variance between the sockets adaptedto receive the blades without injury to the plug.

Such resilient plugs can be molded at low cost and the blades readilyassembled therein after the conductors have been attached to themwithout the use of any\scrgws, rivets or like parts which might workloose. The blades in being assembled are caused to interlock with bodyof the plug to hold the same therein.

Heretofore resilient plugs have been made, but they are objectionable inthat they depended upon distortion of the material of the plug to holdthe blades in operative position. In this condition of distortion of theplug body, the blades were usually unsteady due toinsufficient-frictional contact with the plug body.

In the device of the present invention, the blades may be inserted intothe small end of the plug and into the blade slots and held therein bygripping or looking action between a block on the body of the plug andthe blade, and frictional contact of the slot without any distortion ofthe plug when the blades are in assembled position. The blades are verysolidly anchored in the resilient body and due to the lack of distortionof the body of the plug are very stable in use. Also, when a conductoris connected to the blades, the stability of the blades in the bodyreduces the tendency of movement at the connection which mightinevitably result in breaks in the wire. Also, :the bottom opening ofthe plug will protect the ends of the conductor and insulate the same.

In the plug of the present invention, the blades have a ,plurality ofoppositely positioned tangs projecting from one face thereof to gripoppositely undercut portions of a block in the blade slot. Because ofthis structure of the blade, only a small amount of distortion resultsin the body when the blades are being inserted into the body and thisdistortion disappears entirely when the blades are in final operativeposition.

The method of assembling the blades is a feature of the presentinvention, since it provides for -a simple operation by which theblades, after being connected to the conductor, can be placed in finaloperative position in the plug through the small end of the plug with aminimum of effort and distortion to the body of the plug and whichreadily holds the blades againstlongitudinal movement.

Because of the manner in which the plug and blades are assembled, theplug can be readily molded in one piece. This is advantageous sincemulti-part plugs may become separated at the time when least desired andare .obviously more expensive to manufacture.

Another feature of the invention resides in the simple manner in whichthe resilient plugs can be molded. The cores for blade slots and otherpassages can be readily positioned in the mold and can vbe easilyremoved from the resilient body of the plug after the same has beencompletely molded.

Other features and advantages of ,this invention will appear from thedrawing and the description.

In the drawing Figure 1 is a perspective of the plug with the bladesinserted.

Fig. 2 is a planyiew of the plug.

Fig. 3 is a section along line 3-3 of Fig. 2.

Fig. 4 is a section taken along line 4-4 of Fig. 3.

Fig. 5 is a section taken along line 5-5.0f Fig. 2 with the bladesinserted.

Fig. 6 is a section taken along line 6--5 of Fig. 5.

Fig. 7 is a view showing one-half of .the mold with the core members inplace.

Fig. 8 is a perspective view of the .blades as they are positioned inthe plug.

In my copending application, Serial No. 129,235, filed March.5, 1937,there is provided a resilient attachment plug having blades held thereinwithout distortion of the plug. These blades are provided with notcheson the side edges which interfitted with projections on the sides of theslot. Since the projections extended a substantial distance into theslot, the plug was considerably distorted when the blades were inserted.

The present invention is an improvement on this construction andprovides blades which may be inserted with a minimum amount ofdistortion to the plug and which when inserted are held againstlongitudinal movement by gripping action between the blade and the plug,without any distortion of the plug.

The attachment plug of the present invention, includes a body i made ofresilient moldable ma w. l in S terial and preferably is made in onepiece. provided with a pair oi? slots l i for re and supporting cont cthis W11 blades i2 are insertecii portions thereof project body, while acable it, ti connected to the blades, end of the body through i mergeswith the his entrance passage from tl to be received in t1 shaped lug ITproject. to space the wires in the guide when the blade is insei teninto the blade slot.

According to the present invention, the outer walls l8 of the bladeslots are smooth and uninterrupied so that when the blade enters theslot the free end IQ of the blade may slide along this 'wall withoutobstruction. As shown in Fig. 3, the inner wall of the blade slot isalso substantially continuous, and the space between the walls of eachslot is substantially the thickness of the blade.

Each blade is provided with some anchoring means 2!, in the form of anaperture in the embodiment of the invention herein disclosed, andserving to hold the end of the wire I5 to the blade so that it mayconveniently be soldered thereto.

In assembling the cable and plug, the wires are secured to the bladesand then the blades are inserted through the passage [6 and into theirrespective blade slots H until they take the final position shown inFig. 5 with the free ends projectlng for the engagement of contacts in asuitable receptacle.

To anchor the blades in the blade slots, the present invention providesa form of interconnection between each blade and the body which does notrequire that the body, which is of resilient material, be maintainedunder distortion after the blades are inserted.

For this purpose, the inner wall 20 of each blade slot is formed in partby a block 22 having spaced edges 23 and 24 which are undercut towardeach other, and each blade is provided with tangs 25 and 26 spacedlongitudinally of the blade and directed toward each other andrespectlvely fitting into the undercut edges 23 and 24. The spacingbetween-the edges 23 and 24 and-the tangs 25 and 26 is substantially thecamp so that when the blade is located in the slot the portion of theblock 22 between the edges 23 and 24 will not be under appreciablecompression or distortlon and yet the blade will be held in the slotfirmly against unintentional longitudinal movement in either direction.

It will be seenthat due to the interlocking engagement of the spacedoppositely extending tangs 25 and 26 with the respective undercut edgesor notches 22 and 24 and the walls of the slots, the blades arepermanently held in their respective slots against removal therefromexcept by actual destruction of the plug. The slight movement incidentalto the insertion of the blades into a socket is insufficient to cause adisengagement of the tangs relative to the undercut notches. In fact,longitudinal movement of the blade in either direction increases theunion between the blades and the plug body as this movement causes thetangs 25 or 26 as the same are directed toward each other andrespectively fitting into the undercut notches 22 and 24 to bite intoeither one or the other of the notches dependent upon the direction ofthe movement im-- ported to the blades.

Preieral'lly, the tar by lancing r t portion. of l. a g ml central porti1 J1 tie continuous.

To assemble ti. cable contacts and plug body, the contact l to which thewire ends have been secured is all into the cavity it th the free end0.. th... .Jlade first. Then. the blade is pushed into the slot ii, thefree end riding on the smooth outer wall i2. ilhen the tongs reach theblocl; 22, the portion. of the body be tween the outer wall it and theexterior of the body will yield outwardly, permitting the tangs 25 topass the block 22 until the tangs 26 enter the undercut edges 24 of theblock 22. At this time, the tangs 25 will not have passed the undei cutedges 23, and to cause this to occur the projecting end of the blade ispulled outwardly distorting the material of the block 22 until the tangs25 may enter the undercut edges 23. Upon release of the pulling force onthe blade, the material of the block will resume its natural position,and there will not be any appreciable distor tion of any portion of thebody. To permit this additional movement of the blade, the body is openfrom the undercut edges 23 to the end l3 of the body.

As shown in Fig. '7, the mold 30 has formed therein a cavity of thedesired external contour of the plug. A similar mold section (not shown)is provided to close the mold. Positioned in an aperture in the mold atthe top of the plug is an element 3| carrying a pair of core members 32which are the length of the blade slots. Secured to the edge of theseblade slot core members, as shown in Fig. 7,.are a pair of ribs havingtapered ends 33, which produce the undercut portion 23. The ribs producea pair of slots 34 adjacent the upper end of the blade slots. Positionedin the other end of the mold is a core member 35 for making the commonopening. The end of this core member pngages the end of the blade slotas at 36 to make a complete opening through the plug. A portion 3'! ofthe core member when in position is designed to form the undercutportion 24, After the core members have been inserted in the lower halfof the mold, as shown in Fig. 7, the upper shell or half of the mold islocked thereto and molding material inserted therein. When the moldingoperation is completed, the mold is opened and the plug removed and thecores then withdrawn from the ends of the plug requiring minimumnumber'of operations and minimum amount of effort.-

Variations and modifications may be made within the scope of thisinvention and portions of the improvements may be used without others.

I claim:

1. In an attachment plug, a resilient body having a blade slot thereinprovided with notches undercut towards each other forming a yieldingblock as a part of one wall of the blade slot; a. single thicknessuniplanar blade adapted to be inserted into the slot; and means on theblade and projecting from one face thereof for interlocking engagementwith said notches for permanently locking the blade in the slot when thesame is in the proper assembled position therein, said yielding blockbeing compressible to allow the projecting means on the blade to bepositioned in the undercut notches.

25 and 2B are each mode 2. In an attachment plug, a resilient bodyhaving a blade slot therein; a blade adapted to be inserted into theslot, one wall of said slot having spaced transversely extending notcheswhich are undercut toward each other; and tangs spaced longitudinally ofthe blade projecting toward said wall and fitting in said undercutnotches of the wall of the slot for locking the blade therein when theblade is in the proper assembled position in the body, the resilientmaterial of the wall between the notches being compressible to allow thetangs on the blade to be positioned in the undercut notches.

3. In an attachment plug, a resilient body having a blade slot therein;a blade adapted to be inserted into the slot, one wall of the slothaving spaced transversely extending notches which are undercut towardeach other; and tangs spaced longitudinally of the blade projectingtoward said wall and fitting in said undercut notches of the wall of theslot for locking the blade therein when the blade is in assembledposition in the body, the blade being of such size and shape as toengage the opposite wall of the slot, the lastnamed wall beinguninterrupted for the smooth guidance of the free end of the blade intothe slot, the resilient material of the wall between the notches beingcompressible to allow the tangs on the blade to be positioned in theundercut notches.

4. In an attachment plug, a resilient body having a blade slot therein;a blade adapted to be inserted into the slot, one wall of the slothaving spacedtransversely extending notches/which are undercut towardeach other; and tangs spaced longitudinally of the blade projectingtoward said notched wall and fitting in said undercut notches forlocking the blade in theslot when the blade is in assembled position onthe body, said tangs being spaced apart a distance substantially equalto the distance between the undercut notches of the one wall of the slotso that the walls of the same are substantially free from distortionwhen the blade is in assembled position in the body,

the opposite wall of the slot being uninterrupted for the smoothguidance of the free end of the blade into the slot, said resilient bodyyielding to permit the tangs to be positioned in the undercut notches.

5. An attachment plug comprising a resilient body having a plurality ofblade slots therein formed with a plurality of notches in a wall of eachslot; and a uniplanar blade adapted to be positioned in each blade slotand having tangs in pairs intermediate the ends thereof, said tangsbeing located adjacent the margins of the blade and projecting from theface thereof for engaging the notches and permanently anchoring theblades in place in the slots when assembled therein.

6. A terminal fitting for an electrical conductor comprising a one-piecemolded resilient rubber body having a pair of spaced contactblade-positioning slots in one side of said body; a singleconductor-receiving passage in another side of said body communicatingwith the inner ends of said slots; 2. pair of contact blades each havingan insulated electric conductor secured thereto, said contact bladesbeing simultaneously insertable through the passage into said slotsafter said wires are connected to the respective blades, each bladehaving spaced oppositely-extending barbs formed thereon projectingoutwardly of one face thereof and notches undercut towards each other onone wall of each slot, the barbs being of such size and shape relativeto the size and shape of such slots as to necessitate distortion of thebody to-permit insertion of the blades whereby, after the blades haveemerged into said slots and are in the assembled position, theresiliency of the body is effective to cause the distorted body toreturn to normal conditions so that the barbs are moved into theundercut notches to interlock with one wall of each slot, saidinterlocking engagement permanently anchoring each blade in itsrespective slot.

ARTHUR BROWNSTEIN.

